[Mechanism of the decrease in metacarpal bone mineral content due to oophorectomy].

In order to determine the pathogenesis and pathophysiology of post-oophorectomized osteopenia, we have investigated the bone mineral status and the serum levels of calcium regulating hormones in 250 females. The bone mineral status was measured in 250 [173 pre-menopausal females (controls) and 77 who received oophorectomy] females by microdensitometry in the metacarpal bone. Among these subjects, in some cases who were selected randomly, the serum levels of Alp, Ca, Pi, M-PTH, calcitonin (CT), bone gla protein (BGP), estrone, estradiol and delta 4-androstenedione, and the urinary excretion of Ca and hydroxyproline (OH-pro) as a function of the creatinine ratio were measured. The mineralization indices of bone such as GSmax, GSmin, and sigma GS/D in oophorectomized patients were significantly less than those in controls at ages up to 45 years. On the other hand, the index of periosteal bone resorption (MCI) in the oophorectomized group was less than that in controls at ages up to 50 years. Serum levels of Alp, Ca, Pi and BGP were higher in oophorectomized subjects than in controls. Despite these facts, the serum levels of calcium regulating hormones such as M-PTH and CT in these two groups were significantly different. Urinary Ca/cr and OH-pro/cr ratios were significantly higher in oophorectomized subjects at ages 40-44 than those in age matched controls. These data clearly indicate that oophorectomy causes high turn-over osteopenia.